The Pfizer-Biontec BNT162b2 vaccine has proven efficacy and safety for the prevention of
COVID-19 disease in adults and adolescents aged 12 years and older. Efficacy and safety
were recently shown also for children aged 5-11 years. Side-effects are common, including
some rare but important side-effects such as myocarditis. Myocarditis post Pfizer-Biontec
BNT162b2 vaccination was described mostly among male adolescents and young adults. There
are few data on the immunogenicity of the vaccine and of side effects in children aged
5-11 years. Therefore, our aim is to determine the immunogenicity and to describe the
local or systemic reactogenicity events after vaccination with the BNT162b2 COVID-19
vaccine in children aged 5-11 years.

This is a prospective cohort study assessing the immunogenicity of the BNT162b2 COVID-19
vaccine in children. The study population will be composed of children aged 5-11 years at
the Schneider Children's Medical Center, with no contraindication for COVID-19
vaccination. Upon enrollment in the study, participates will be requested to complete an
enrollment questionnaire and a blood sample for baseline serological evaluation will be
obtained.

The study follow-up period will be 6 and a half months from receipt of the first dose of
the vaccine. The study will last 6 months from the date of the approval of the study
protocol.

Blood samples for immune response evaluation will be taken at intervals of 28 days (+/-
14) until 6 and a half months from receipt of the first dose of the vaccine. Samples will
be tested for antibodies to SARS-CoV-2 at the Microbiology Laboratory at the Rabin
Medical Center. Symptomatic participants with any respiratory symptoms or other symptoms
suggestive of COVID-19 disease will be tested for SARS-CoV-2 by RT-PCR, at laboratories
certified by the Ministry of Health.